Comment 7 for bug 1449295

App icons are, or will be, also rendered by content-hub in its “Open With” dialog; by indicator-sound when a player is registered with Mpris; by url-dispatcher in its “Use App” dialog; and by any app that uses its own icon in a notification. (Presumably the notification cases can’t be fixed in notify-osd and indicator-messages themselves, because they don’t know whether the icon they receive is an app icon or something more specific.) That almost certainly still isn’t a complete list.

These “oh, we need to fix this bug here too, and here, and here” comments bolster my proposal in wontfixed bug 1363015: there should be a toolkit element for rendering an app’s icon in the current standard style. As long as every place that renders app icons has to include its own code for making a transparent background opaque, along with all their other details (icon location in click/snap packages, aspect ratio sanity-checking, rounded corners, relief/shadow, etc), then whenever the rendering of app icons changes, time will be wasted on multiple implementations and some of them will be forgotten or diverge accidentally.